Camaro99SS

iTrader: (3)

A friend/former boss just bought an 05 Silverado Z71 4 door 5.3 with a conversion package that includes a ~6" lift along with 35" tires. His truck is a turd though and gets worse mileage on the interstate then in the city because it's always having to downshift and lug. It's gotten as high as 14 in the city with a fairly light foot, but it goes down to around 11 on the interstate where 70-80mph cruising speeds are common.

My question to you all is between 4.10's and 4.56's which would be the best choice? 4.10's would put him about near stock rpm cruising rpm's, but I think 4.56's would be the best all around choice for power and mileage with the added mass of taller tires and more ride height. The truck sees about half city and half highway driving and it won't be used for towing, at least in the near future. Also, since this will be a 1 time thing, what programming tool would be best to calibrate the speedometer? thanks in advance

Jason

v8

iTrader: (10)

go with the 4.56's with the 35" tires. he should get better gas milage in town and on the hwy.

Avalanche2002

With 35's he should go with the 4.56's.

Camaro99SS

iTrader: (3)

Anyone else have any experience with either of these gears with 35's?

Jason

tblrk1980

i had 4.56 with 33's when i lived in colorado. Great for wheelin in the mountains, but you can get buy with 4.10's around town. If gas aint no problem i would do 4.88's with the 35's....much less trouble turning those tires, and the truck would still be pretty peppy.

bluecajun5.3

iTrader: (31)

my buddy has the same truck, z-71 ext cab but with 4.10's from the factory. it pulls good even with them 35's and his gas mileage didn't drop much.